Electromagnetic relay



Dec. 29, 1931. A. B. PREUSS 1,838,737

ELECTROMAGNETIC RELAY Filed March 12, 1928 Fig. 1 3 1 ram F1123: andar' Bruno F1- E11! 5 Patented Dec, 29, 1931 UNITED STATES PATENT OFFICE ALEXANDER BRUNO PREUSS, BERLIN-CHARLOTTENBURG, GERMANY, ASSIGNOR TO SIEMENS & HALSKE AKTIENGESELLSCHAFT, OF SIEMENSSTADT, NEAR BERLIN,

GERMANY ELECTROMAGNETIC RELAY Application filed March 12, 1928, Serial No. 260,998, and in Germany June 4, 1927.

This invention relates in general to electromagnetic relays, more particularly to such relays which are marginal in their 0 eration,

and which will operate one set 0 springs when energized to a certain strength, and operate an additional set of springs when more strongly magnetized, and the principal object of the invention, briefly stated, is the provision of a new and improved marginal two-step relay, the improvements tending to make the relay more reliable in its operation over a wider range of spring loading, and with a narrower range of difierence between the strengths of magnetization required to operate the relay in its two stages.

Two-step marginal relays have been devised heretofore, and numerous devices have been employed to secure a reliable operation of the relay when itis under heavy load, that is, when it is moving a large number of springs. These relays have employed an armature which moves in the same direction during both steps of its operation, and because of the momentum of the moving parts, and the shortening of the air gap when the armature moves to its first step, it was necessary to provide a heavy spring load to be picked up by the armature at the end of its first step, to stop it there, and consequently a large increase in magnetization was required to move the armature through its second step. At best, relays of this type, designed heretofore, have been limited to a relatively light spring load, in order that a a reliable operation could be secured on both steps. To improve this condition, I have provided, as a further object of my invention, a new and improved two-step relay, in which the armature is moved in one direction during its first step and in the opposite direction during its second step, this arrangement permitting me to add more relay springs to be operated by the armature'in each of its steps, and to decrease the difierence in magnetization required between the two steps.

This and further objects,not specifically mentioned here, will be apparent from a reading of the detailed specification and claims which follow. 8

The drawings comprising Figs. 1 to 5, in-

clusive, show sutficient details to enable a clear understanding of two different relays made in accordance with the objects of my invention.

Figs. 1, 2, 3, and 4, show one type of relay, and Fig. 5 shows a modification adapted for a particular use. Fig- 1 shows the relay in its normal position, Fig. 2 shows the same rebeing held thereby by a retaining screw. The

armature consists of the usual magnetic member, and the spring operating the extension which projects along the outside edge of the heel piece and rests against the bushing which operates the springs when the armature moves. The usual iron core electromagnet is also mounted on the heel piece 1, this electromagnet being altered by the attaching of the U-shaped magnetic member 5 to the core 7 at the armature end of the core. This member 5 may be attached to the core by welding. Attached to the U-shaped member 5 is the magnetic auxiliary pole 6, which is of relatively small cross section. A nonmagnetic residual screw is provided in this member 6, to control the air gap between the armature and the member 6 when the relay is operated in its. first position.

When the core of the electromagnet is energized to the low magnetization necessary to operate the relay in its first step, the magneto motive force set up in the end of the core 7, and in the auxiliary pole piece 6 is substantially the same. When normal, the armature 2 rests in a position slightly nearer the auxiliary pole piece 6 than the main pole piece 7 and because of the shorter air gap, flux flows from the pole piece 6 into the armature thence through the heel piece into the core 7, and moves the armature 2 in a counterclockwise direction over against the residual screw in the pole piece 6. The spring operating lever o the armature is moved down, closing the spring assembly 4 to complete the operation of the relay in its first step. This weak magnetization produces suflicient flux to saturate the auxiliary pole piece 6.

When the circuit leading to the relay is altered to increase the amount of current flowing through the coil, higher magneto motive force is built up at the pole piece 7, but because of the saturated condition of the auxiliary pole piece 6, practically all of the additional flux generated in the electromagnet is driven across the main air .gap from the pole iece 7 to the armature 2. When this flux as built up to a suflicient strength to attract the armature 2 away from the auxiliary pole piece 6, the armature moves in a clockwise direction comipg to rest against the main ole piece 7. The spring operating lever of t e armature moves away from the sprin assembly 4 and towards the spring assem 1y 3, restoring the former to its normal position and operatin the latter, to complete the second step 0 the operationof the relay. Since there is a residual air ga between the auxiliary pole iece '6 an the armature 2, the amount 0 increase in the magnetization force necessary to move the armature away from the auxiliary pole piece and into the engagement with the main pole piece is relatively small. When the electromagnet is deenergized, the armature is restored to its normal position under the tension of the main assembly 3.

Referrin now to Fig. 5, it will be seen that I have mo ified the structure shown in the other figures by forming the auxiliary pole piece 5 of one piece, and providing a threaded cylindrical member 6 which fits into this auxiliary pole piece and is adjustably located with respect to the armature 2. By adjustment of the member 6, the normal air gap between the armature 2 and the auxiliary pole may be varied at will. If desired, the face of the auxiliary member 6 can be covered with a non-magnetic material to provide the residual air gap customary in such relays. The operation of the relay in Fig. 5 is identical with that already explained and need not be repeated in detail.

the operation, it is impossible to operate both of the spring sets simultaneously. --Moreover since the armature is definitely brought to rest by coming into contact with the residual screw of the back stop at the end of the first step, a higher magnetizing force can be used for this step, and consequently a larger spring will operate durin it. If the auxiliary pole piece. is made 0 a high rmeable soft iron, or permgloy, flux will available to to a strength above the saturation point Obviously since the armature must move ini opposite directions to operate the spring set controlled in the first and second stages of operate a heavy spring load on the first step, without requiring an abnormally high magnetization to break the armature away from the auxiliary back stop and into engagement with the main pole piece during the second step of the operation of the relay.

While I have chosen to show my invention in connection with a particular type of relay, I have done so by way of example only, as there are many modifications and adaptations which will be apparent to one skilled in the art which can be made without departing from the scope of the invention.

Having thus described my invention, what I consider new and desire to have protected by Letters Patent, is pointed out in the appended claims.

What is claimed is:

1. In an electromagnetic relay, an armature, a core, said armature moving in one direction responsive to a magnetization of said core in one direction and moving in the opposite direction responsive to an increase in the magnetization of said core in the same direction, and different sets of springs operated by said armature during each of said movements, and for normally maintaining said armature in a neutral position when said core is not magnetized.

2. In an electromagnetic relay, a main and an auxiliary pole piece, an armature interposed between said pole pieces, springs engaging said armature and holding it in a position away from both of said pole pieces but nearer to said auxiliary pole, means for magnetizing said pole pieces to a certain strength to move said armature toward said auxiharyaole and for subsequently magnetizing sai pole pieces to a greater strength to move said armature toward said main pole.

3. In an electromagnetic relay, a main and an auxiliary pole piece, said main pole piece having a greater cross sectional area than said auxiliary pole piece, an armature, springs engaging said armature and holding it in a position away from both pole pieces but nearer to said auxiliary pole piece, means for magnetizing said relay to a strength below the saturation point of said auxiliary pole piece to move said armature against that pole and to subsequently magnetize said relay of said. auxiliary pole piece to move said armature awa from said auxiliary pole and toward sai main pole piece.

4. In an electromagnetic relay, a core, a main and an auxiliary pole piece magnetically connected to one end of said armature magnetically connected to the opposite end of said core, springs engaging said armature and holdin in a position away from both of said poll: pieces but nearer to said auxiliary pole, means for magnetizing said core to a certain stren h to move said armature toward said auxihary pole and for core, an

an auxiliary pole piece, an armature, springs engaging said armature to hold it in a position thatincludes a large air gap in the magnetic-path from said main pole piece to said armature and a smaller air gap in the magnetic path from said auxiliary pole piece to said armature, means for magnetizing said relay to move said armature first to shorten the small air gap and lengthen the large and then to shorten the large air gap and to lengthen the small.

6. In an electromagnetic rela a mam and an auxiliary pole piece, an arm ture, springs engaging said armature to hold it in a position that includes a large air gap in the magnetic path from said main pole piece to said armature and a smaller air gap in the magnetic path from said auxiliary pole piece to said armature, means for varying the length of said small air gap without altering the length of said large gap and means for magnetizing said relay to move said armature first to shorten the small air gap and lengthen the large and then to shorten the large air gap and to lengthen the small.

7. An electromagnetic relay having a heel piece upon which are mounted an electromagnet and a plurality of groups of springs, a knife edge on the end of said heel piece, an armature pivoted against such knife edge, and means for rendering said armature re-. sponsive to an initial energization of said magnet to move said armature in one direction to operate, certain of said springs, and responsive to a further energization of said magnet in the same direction, to move said armature in an opposite direction to operate the other of said springs.

8. An electromagnetic rela having a heel piece upon which are mounte an electromagnet and a plurality of groups of springs, a knife edge on the end of said heel piece, an armature pivoted against said knife edge,

means including an auxiliary pole piece mounted on the armature end of said electromagnet for rendering said armature responsive to an initial energization of said electromagnet in one direction to operate a certain one of, said springs, and means responsive to a further energization of said electromagnet in the same direction to move said armature in the opposite direction to restore said opsprings.

lel therewith to form a U-shaped structure so that said armature lies between the pole pieces, and means for variably magnetizing said core to move said armature either against said main or said auxiliary pole pieces, and different sets of contact springs operated by said armature in each of its movements and for normally holding said armature in a neutral position between said main and auxiliary pole pieces. W a

10. In an electromagnetic relay, a core, a

heel piece attached to an end of said core and having an armature pivoted on the other end opposite the other end of said core, a main pole piece attached to the armature end of said core, an auxiliary pole piece'spaced opposite said core and attached to said main pole piece, means responsive to the variable magnetization of said core for moving said armature to a position either against said main or said auxiliary pole pieces, and'two sets of contact springs-on said heel piece operated by said armature, one set being oper' ated in one position of the armature and the other set in the other position, both sets of contact springs normally maintaining said armature in a neutral position between said main and auxiliary pole pieces.

In Witness whereof, I hereuntosubscribe my name this 13th day of February, A. D.

ALEXANDER BRUNO PREUSS. 

